This invention relates to steel railway boxcars and, in particular, to means for providing smooth interior walls for such boxcars.
Producers of pressure sensitive cargo such as newsprint and rolled paper for some time have been complaining about damage to cargo caused when the heavy paper rolls lean against the interior wall of a steel boxcar. Butt welds and plug welds, used to attach the side sheets to the side post, have raised reinforcement on them that damage the outer layer of the paper roll when the weight of the paper roll leans against the interior wall.
Many boxcar manufacturers are attempting to build steel boxcars in a manner that interior seams are not presented to the cargo or, if they are presented, pose no damage risk as they are smooth with the adjacent side walls.
Although progressive strides have been made in the art of applying the butt weld bead and/or grinding off the excess weld reinforcement along the vertical seam welds, the paper industry has not generally been impressed with railcar manufacturer""s results. There is a great demand in the newsprint/paper industry for a xe2x80x9czero protrusionxe2x80x9d or smooth interior boxcar side wall.
Accordingly, the invention in one aspect provides a steel boxcar side wall construction including a pair of wall side sheets joined together by a lap joint configuration defined by one sheet of said pair having an offset section along that edge of the sheet to be joined to the other of said sheets with the lateral offset distance (d) of said one sheet being equal to the thickness (t) of the other said sheet. The sheets are overlapped and welded together along said offset section such that inner surfaces of the two sheets thus joined lie substantially in a common plane with no or substantially no weld material lying inwardly of said common plane. This side wall construction is capable of presenting a substantially smooth interior surface to cargo being carried in a boxcar employing said side wall construction.
Further features of the invention will become apparent from the following description and the appended claims.